Hereditary progressive dystonia with marked diurnal fluctuation (Segawa syndrome) in Taiwan.

Since 1988, we have diagnosed 6 cases of hereditary progressive dystonia with marked diurnal fluctuation (HPD) in Taiwan. All cases presented with clinical features similar to those described by Segawa. They consisted of four sporadic and two familial cases. The age at onset ranged from 18 months to 8 years. There is a female predominance of 4:2. All of them showed mild postural tremor and postural dystonia manifested initially by flexion-inversion of a foot. However, unlike Segawa's description, side preference to the right (4:2) was noticed. Neck and axial muscles were not or were minimally involved, except a case presenting with retrocollis and tilting of the neck. These symptoms showed remarkable diurnal fluctuation which became aggravated towards the evening and alleviated in the morning or after rest. Response to L-dopa was dramatic, independent of the duration of illness, and no adverse effect of L-dopa has been observed. Our experience suggested that 10 mg/kg/day of L-dopa may be an optimally effective dose for treatment of patients with HPD. Neurophysiological, neuroradiological and biochemical studies were all normal except in one case who showed prolonged somatosensory potential latencies and white matter changes on MRI. Change of dopamine and its metabolites in CSF, plasma and urine had been investigated in one case.